The present invention relates generally to crop harvesting machines containing a conditioning apparatus to condition crop material fed thereto and, more particularly, to a biasing mechanism for urging the upper conditioning roll toward engagement with the fixed lower roll.
Mower conditioners typically include a crop gathering header which is normally provided with a cutterbar operable to sever standing crop material from the field, a conveying device, such as a rotating reel and/or an auger, to convey the severed crop material rearwardly over the cutterbar, and a conditioning mechanism mounted rearwardly of the cutterbar to receive severed crop material from the reel or auger and effect a conditioning of the severed crop to hasten the drying thereof. Although flail-type conditioners have enjoyed some success, conditioning mechanisms in North America generally include a pair of vertically spaced, counterrotating conditioning rolls operable to receive severed crop material therebetween to effect a conditioning thereof.
Because of varying thicknesses of materials passing between the counterrotating conditioning rolls, the upper conditioning roll has traditionally been mounted on pivot arms to permit a generally vertical movement toward and away from the fixed lower conditioning roll. To assure maximum engagement with the crop material to be conditioned, the upper conditioning roll is usually engaged with a biasing mechanism to urge the upper conditioning roll toward engagement with the lower conditioning roll. As the upper roll moves away from the lower roll, the biasing force is normally increased.
More recent biasing mechanisms for mower conditioners have utilized torsion bars to exert the biasing force on the upper conditioning roll. Typically, torsion bars extend from a central mounting mechanism outwardly to corresponding linkages interconnecting the torsion bar to the pivot arms for the end of the upper conditioning roll. An adjustment mechanism bridges between the mounting mechanism and the conditioner frame to permit a varying of the minimum biasing force exerted on the upper conditioning roll when the upper roll is as close to the lower conditioning roll as will be permitted by the structure limiting movement of the upper conditioning roll. Such biasing systems are complex and expensive to manufacture. Accordingly, it would be desirable to provide an improved torsion bar biasing mechanism that would be simpler and less expensive to manufacture and maintain.